Researchers say that men who use cell phones frequently have significantly lower sperm counts than those who don't use cell phones at all.

The observational study of 361 men undergoing evaluation for infertility was conducted in Cleveland, New Orleans and Mumbai in India, according to the American Society for Reproductive Medicine.

Of men in the group with a normal sperm count, those who didn't use cell phones had sperm counts averaging 86 million per millilitre vs. 50 million per millilitre for those using a cell phone four or more hours a day. The spontaneous movement and the form of the sperm also seemed to be negatively affected by cell phone use, the research showed.

The researchers cited cell phones' electromagnetic radiation and the heat they generate as possible reasons for sperm differences between cell phones users and those not using them. Further research needs to be done, however, to better understand why the differences exist, researchers said.

Not everyone in the field is fazed by the results. Epidemiologist Linda Erdreich of scientific and engineering firm Exponent was quoted saying that cell phones don't heat body tissue enough to cause big changes; she also noted that the lowest average sperm count mentioned in the study - 50 million per millilitre - is not nearly enough to be considered abnormal.

Of course, the chances of cell phones being held in a spot where they might affect sperm generation seems a lot less likely than people holding their laptop computers in such a place. Research has emerged in the past associating the heat from laptops with lower sperm counts.